It's a fascinating glimpse inside the ATF’s battle against violence and crime in Southeast Michigan. The vaults at the Detroit Field Division house the weapons seized during criminal investigations, and the 7 Investigators got to see what’s normally kept under lock and key.

Four vaults inside the Bureau of Alcohol, Tobacco, Firearms, and Explosives Detroit Field Division are loaded with thousands of weapons.

ATF Special Agent Donald Dawkins says the guns have all been seized and stored as evidence, as part of their criminal investigations in Southeast Michigan.

“This is a very old firearm, but obviously, it’s still functional,” said Dawkins, holding up an older rifle.

Inside the vaults you’ll find vintage weapons, semi-automatic rifles and even AR-15’s, which Dawkins says more common than you may realize in Detroit.

“People think these are sexy and you see them, they can do a lot of damage, obviously,” said Dawkins.

Whether it’s gun trafficking cases or massive motorcycle gang investigation, the ATF has to store all of the evidence that agents seize until the verdict is in and every appeal is exhausted.

There are even guns that have been “enhanced” by their former owners.

“This is the Ruger, but it’s from one of our motorcycle gang investigations and they just added some opticals, some flashlights. It looks pretty menacing,” said Dawkins, holding up a semi-automatic gun with several lights attached to it.

While the rows and rows of long guns in both vaults look intimidating and impressive, the biggest haul among the seized weapons is always handguns.

In each vault there are stacks and stacks of evidence boxes containing the smaller firearms.

All of these guns that are seized are tracked and analyzed using the ATF’s Firearms Tracing System.

That’s a database that allows the feds to track where a gun originated -- and perhaps who it was stolen from -- before it was used to commit a crime. That’s why Dawkins says it’s so important for you to tell the police if your firearm has been stolen.

“It may solve a number of crimes, it’s very important. It’s not a tool to be taken lightly,” said Dawkins.

ATF data shows that in 2012, 4,360 firearms were recovered and traced in Michigan and more than half of those guns were recovered in Detroit.

Another tool the ATF urges state and local police departments to use: their NIBIN, or National Integrated Ballistic Information Network. That’s the system where ballistics from shootings can be compared against data from guns across the country.

“It’s vital, because you might have a firearm, you have a homicide victim – you may have the firearm, and you may have that particular case solved. But if you get that firearm and trace it, it may lead to another homicide, it may lead to an armed robbery,” said Dawkins.

ATF agents say the ballistics and tracing systems are only as good as the data that’s entered into them, so they urge all of their local law enforcement partners to use it as often as they can.